Electric Fields

Electric Field Lines

We have calculated the value
of the Electric field. It is also useful to visually construct Electric
field lines which connect all the electric fields or are tangent
to the electric field at all points in space.

From our most basic definition of the electric field,

E = F/q

or

F = E q

you already know that the electric field points in the direction
of the force on a positive test charge. That means the electric field
points away from a positive charge and points toward a negative
charge. In terms of the electric field lines, we can say that
the E-field lines originate on a positive charge and terminate on a negative
charge.

More examples:

The magnitude of the electric field is stronger (or
greater) where the electric field lines are closer together and the electric
field is weaker (or smaller) where the electric field lines are farther
apart.